Britain has backed a plan to expand Europe’s busiest airport, Heathrow, in a push to grow trade and make Britain a solid international competitor. The decision comes after decades of debating how to accommodate travelers and business flights at London’s two crowded airports.

Prime Minister Theresa May was expected to call for a new runway at Heathrow during a Tuesday meeting with ministers, kickstarting a plan that has languished for 25 years as leaders have debated whether Heathrow or Gatwick, another airport to the south, should bear the brunt of increased flight traffic. Britain’s vote to depart from the European Union spurred a decision on expansion, as additional runways will be needed to boost the nation’s trade ties and allow it to compete with EU cities like Paris, Amsterdam, and Frankfurt.

But a real change to Heathrow likely won’t come soon. The expansion, which officials estimate will cost between $17 and $22 billion, is slated to be completed by 2025 but could face legal challenges from local councils, community organizations, and environmental groups. The runway will be the first new one built in London in 70 years.

"There will be challenge and opposition whatever option we take," Transport Minister Chris Grayling told BBC. "We have to, in my view, take a decision that is in the interests of our nation, what delivers the best connectivity, the right approach for the future at a time when we want to grow international trade links, open up new opportunities."

The Heathrow expansion is much more costly than the $9 billion proposed expansion to Gatwick. But officials say the nation’s decision to leave the EU has pushed them to select Heathrow, which serves more air freight and receives tourists from farther destinations. Both currently operate near capacity.

Some have decried the plan to pursue the more expensive option. While taxpayers will share some of the burden, passengers will likely be saddled with the costs of expansion on their tickets.

If Heathrow "were to react very quickly saying from 1 January we're going to add £10 [to airport charges], we wouldn't react very well,” British Airways chief executive Alex Cruz told BBC. "We would very much oppose such a move."

Environmentalists worry that the expansion, which would increase the number of annual flights from 480,000 to 740,000, would pose a threat to the environment locally and prevent Britain from reaching its carbon-cutting goals.

“Expansion at Heathrow, or any other airport, will create a serious obstacle to the UK meeting its greenhouse gas and air quality targets,” Joanna Haigh, co-director of the Grantham Institute for Climate Change and the Environment, told The Independent. “Increased flights, more traffic on roads in and around the airports, and emissions from the new construction will add to an already woeful situation, particularly in London and the South East of England.”

To accommodate increased air traffic, other sectors of the economy may have to cut emissions by 80 percent by 2050, a feat that could hamper business growth elsewhere. Greenpeace has vowed to challenge the move in court and launched an appeal for funds to cover legal proceedings in a judicial review of the plan.

Others who oppose the decision, such as Foreign Secretary Boris Johnson, have expressed doubt about the plan’s viability.

"I think it very likely it will be stopped," he said. "We have been here before and we are going to see an inevitable fight in the courts and I think the chances of success for the proponents of the third runway are not high."